Wireless power transmission system

ABSTRACT

The wireless power transmission is a system for providing wireless charging and/or primary power to electronic/electrical devices via microwave energy. The microwave energy is focused to a location by a power transmitter having one or more adaptively-phased microwave array emitters. Rectennas within the device to be charged receive and rectify the microwave energy and use it for battery charging and/or for primary power.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/052,828, filed on Oct. 14, 2013, which is a continuation of U.S.patent application Ser. No. 13/851,528, filed on Mar. 27, 2013, whichissued as U.S. Pat. No. 8,558,661 on Oct. 15, 2013, which is acontinuation of U.S. patent application Ser. No. 13/443,355, filed Apr.10, 2012, which issued as U.S. Pat. No. 8,410,953 on Apr. 2, 2013, whichis a continuation of U.S. patent application Ser. No. 12/861,526, filedAug. 23, 2010, which issued as U.S. Pat. No. 8,159,364 on Apr. 17, 2012,which is a continuation-in-part of U.S. patent application Ser. No.11/812,060, filed Jun. 14, 2007, which issued as U.S. Pat. No. 8,446,248on May 21, 2013, all of which are incorporated herein by reference as iffully set forth.

FIELD OF INVENTION

The present invention relates generally to power transmission systemsand battery chargers, and particularly to a method and system forwireless power transmission by microwave transmission to power a devicerequiring electrical power.

BACKGROUND

Many portable electronic devices are powered by batteries. Rechargeablebatteries are often used to avoid the cost of replacing conventionaldry-cell batteries, and to conserve precious resources. However,recharging batteries with conventional rechargeable battery chargersrequires access to an alternating current (A.C.) power outlet, which issometimes not available or not convenient. It would therefore bedesirable to derive power for a battery charger from electromagneticradiation.

While solar-powered battery chargers are known, solar cells areexpensive, and a large array of solar cells may be required to charge abattery of any significant capacity. Another potential source ofelectromagnetic energy that would provide power to a battery charger ata location remote from the A.C. power mains is microwave energy, whichmight be derived from a solar powered satellite and transmitted to earthby microwave beams, or derived from ambient radio frequency energy fromcell phone transmitters and the like. However, there are severalproblems associated with the efficient delivery of power by microwavetransmission that have precluded the use of dedicated terrestrialmicrowave power transmitters for the purpose.

Assuming a single source power transmission of electro-magnetic (EM)signal, an EM signal gets reduced by a factor of 1/r² in magnitude overa distance r. Thus, the received power at a large distance from the EMtransmitter is a small fraction of the power transmitted.

To increase the power of the received signal, we would have to boost thetransmission power. Assuming that the transmitted signal has anefficient reception at three centimeters from the EM transmitter,receiving the same signal power over a useful distance of three meterswould entail boosting the transmitted power by 10,000×. Such powertransmission is wasteful, as most of the energy would be transmitted andnot received by the intended devices, it could be hazardous to livingtissue, it would most likely interfere with most electronic devices inthe immediate vicinity, and it may be dissipated as heat.

Utilizing a directional antenna has several challenges, some of whichare: knowing where to point it; the mechanical devices needed to trackit would be noisy and unreliable; and creating interference for devicesin the line of sight of the transmission.

Directional power transmission generally requires knowing the locationof the device to be able to point the signal in the right direction toenhance the power transmission efficiency. However, even when the deviceis located, efficient transmission is not guaranteed due to reflectionsand interference of objects in the path or vicinity of the receivingdevice.

Thus, a wireless power transmission system solving the aforementionedproblems is desired.

SUMMARY

The wireless power transmission is a system for providing wirelesscharging and/or primary power to electronic/electrical devices viamicrowave energy. The microwave energy is focused to a location inresponse to receiving a beacon signal from a beacon device by a powertransmitter having one or more adaptively-phased microwave arrayemitters. Rectennas within the device to be charged receive and rectifythe microwave energy and use it for battery charging and/or for primarypower.

The device to be charged reports the received beam signal strength atthe rectennas to the power source via the side channel. This informationis used by the system to adjust the transmitting phases of the microwavearray emitters until maximum microwave energy is reported by the deviceto be charged.

Alternatively, the array elements can be set to receive a calibrationsignal from the device being charged. Each array element candetect/report phase information from the received calibration signal.Subsequently, each array element uses the detected phase for thatelement as a guide to the transmitting phase back to the device beingcharged.

Mirror focal points caused by, for example, flat, two dimensional arraysare minimized by physically configuring the microwave array emitters ina substantially non-uniform, non-coplanar manner.

These and other features of the present invention will become readilyapparent upon further review of the following specification anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an environmental, perspective view of a first embodiment of awireless power transmission system according to the present invention.

FIG. 1B is an environmental, perspective view of a second embodiment ofa wireless power transmission system according to the present invention.

FIG. 2A is a perspective view of the phased array net antenna for amicrowave transmitter in a wireless power transmission system accordingto the present invention.

FIG. 2B is a diagrammatic view of a power transmission node in awireless power transmission system according to the present invention.

FIG. 3A is a block diagram of the first embodiment of the wireless powertransmission system according to the present invention.

FIG. 3B is a block diagram of the second embodiment of the wirelesspower transmission system according to the present invention.

FIG. 4 is a block diagram of an alternative first embodiment powertransmitter.

FIG. 5 is a block diagram of an alternative second embodiment powertransmitter.

FIG. 6 is block diagram of a controller.

FIG. 7 is block diagram of an alternative receiver in accordance withthe first embodiment.

FIG. 8 is a block diagram of an alternative receiver in accordance withthe second embodiment.

FIG. 9 is a block diagram of a receiver battery system.

FIG. 10 is an example battery system power line diagram.

FIG. 11 is an alternative receiver in accordance with the firstembodiment.

FIG. 12 is an alternative receiver in accordance with the secondembodiment.

Similar reference characters denote corresponding features consistentlythroughout the attached drawings.

DETAILED DESCRIPTION

As shown in FIGS. 1A-1B, the present invention includes a system 100 a,or alternatively system 100 b, for providing wireless charging and/orprimary power to electronic/electrical devices, such as laptop computer102, or the like, via microwave energy. In either system 100 a or system100 b, power transmission grid 101 a or alternative power transmissiongrid 101 b can obtain operational power from the A.C. mains via powercord P being plugged into power outlet O. The microwave transmissionfrequency is preferably an available FCC unregulated frequency having asuitable wavelength. Since the wavelength can limit resolving power ofthe phased array 101 a or alternative phased array 101 b, a preferredfrequency, although not limiting the choice of other frequencies thatthe system may operate on, has been determined to be 5.8 GHz (5.17 cmwavelength), which is suitable for power transmission to such devices asa laptop, cell phone, PDA, etc., over distances on the scale of a room,auditorium, or the like.

As shown in FIGS. 1A-3B, the microwave energy is focused onto a deviceto be charged by a power source 300 connected to one or moreadaptively-phased microwave array emitters 204, i.e., antennae orradiators. According to the present invention, the microwave energy fromthe adaptively-phased microwave array emitters 204 may be focused ontothe device without the need to know the location of the device. As shownin FIGS. 1A, 1B, and 3A-3B, preferably highly efficient rectennas 340 (arectenna is a rectifying antenna that converts microwave energy directlyinto direct current (D.C.) electricity; such devices are known in theart and will not be described further herein) within the device to becharged 102 receive and rectify the microwave energy and use it forcharging battery 370 via charging and/or for primary power to the device102 as determined by control logic 350. In a first embodiment, acommunications channel is opened between the wireless power source 100 aand power receiver 330 b in the device to be charged 102 on a frequencyother than the frequency used to convey power.

The device to be charged 102 relays a received beam signal strength atthe rectennas 340 over the communications channel 110 a to a receiversection of communications device 320 in the power transmitter 330 a ofsystem 100 a via a signal from a transmitter section of communicationsdevice 360 in the power receiver 330 b. This information is used bycontrol logic 310 of the system 100 a to power up, power down, andadjust the transmitting phases of the microwave array emitter nodes 204until a maximum microwave energy beam 301 is radiated by the array 110a, as reported by the device to be charged 102.

Each emitter 204, being connected to a single source of the desiredtransmission frequency, can transmit a signal with a specific phasedifference, which is a multiple of π/2. The π/2 phase increments areexemplary only, and other phase increments such as π/4, π/8, π/16, andthe like, are possible. Preferably, power is not adjusted, except thatthe emitter 204 can be turned off or turned on to a desired phase.

As most clearly shown in FIGS. 2A-2B, vertical and horizontal cablesintersect at each array node 204. This configuration applies to eitherarray 101 a or array 101 b. Within vertical cable 202, wire 210 is azero phase feed line. Wire 212 is a 1/2π phase feed line, and wire 209is a vertical control line. Similarly, within horizontal cable 200, wire214 is a π phase feed line. Wire 216 is a 3/2π phase feed line, and wire211 is a horizontal control line. Control lines 209 and 211 can beconnected to the controller 310 in order to control which phase isactive on any given node 204. Single antenna control can be on a chip206, while the actual node radiator or antenna 208 may be formed as acircular element surrounding the geometric center of the node 204. Itshould be understood that either a single controller or a plurality ofcontrollers may control one or more of power transmission grids.

An exemplary algorithm of control logic 310 for system 100 a might be asfollows: (1) the power receiver 330 can use the communications channel110 a to declare its presence to any transmitters 330 a in the vicinity;(2) the power transmitter 330 a may communicate its presence on thecommunications channel 1110 a and start transmitting with only one ofits antennae 208 or nodes 204; (3) the power receiver 330 b mayacknowledge receiving the faint signal on the communications channel 110a; (4) the power transmitter 330 a switches on another antenna 208 ornode 204 with a default phase of zero and may ask the receiver 330 bover the communications channel 110 a for signal strength; (5) the powerreceiver 330 b may send back a signal indicating that the receivedsignal is higher, the same, or lower than before; (6) if the signal islower than or the same as before, the controller 310 may cause the phaseat node 204 to increase its phase by 1/2π and request another signalstrength transmission; (7) steps 5 and 6 are repeated for all phases;(8) if no increase in signal strength is observed then that particularnode 204 is switched off and another node is used in the process,repeating from step 4; (9) steps 4-6 are repeated until all emittersnodes are in use.

In another example, step (6) may include increasing the phase over athree-phase cycle that includes 0, 1/2π, and 5π/4 radians. In thismanner, the approximate shape of the whole sinusoidal curve may bedetermined. Accordingly, the phase angle of the peak power may bedetermined. Also, since when adding up tuned antennas, the next addedantenna received power may only be a small percentage of the total powerreceived. Thus, adding the second antenna may increases the power by 4×,while adding the 101st antenna may add 2% to the power and the 1001^(st)may add 0.2% to the total power received. This may make it difficult todetect the actual power gain/loss from the tested antenna. Therefore,only a few antennas may be powered up during the testing cycle, and thephases for each antenna tested may be remembered. Once the full array'sphases have been determined, all the elements may be switched on todeliver power.

Alternatively, all of the antennas in the power transmitted may bere-tuned, possibly by moving their phases slightly around their currentvalues, and detecting the impact on the received signal. If it improvesin one direction, (e.g., advancing or retarding the phase), the phasemay continue to be cycle/incremented until there is no improvement toeither side. This will depend on the ability to detect the change inreceived power level for a large array, otherwise, the whole array mightbe required to switch off and re-establish the phases from scratch.

In a second embodiment, as most clearly shown in FIGS. 2B and 3B, eacharray element or node 204 can be set to receive a calibration signalfrom a calibration transmitter 460 in the power receiving system 330 b.Each array element or node 204 can send the received calibration signaldetected at that node 204 to the control logic 310 via data line 303.Subsequently, either controller 310, controller 206, or both controllersin combination may set each array element or node 204 to the detectedphase for that element as a transmitting phase in order to send anoptimized power transmission 301 back to the power receiver 330 b. Inboth embodiments 100 a and 100 b, a configuration memory device may bein operable communication with the controller logic 310 in order toenable the array to transmit power to a specific location or “hotspot”without first having to communicate to the device to be charged 102.This feature is useful in sending power transmission 301 to the deviceto be charged 102 when the device to be charged 102 has no reserve powerto establish communications channel 110 a or 110 b.

Alternatively, the second embodiment may operate as follows to utilizetwo way capabilities in the receiver and every transmitter antenna, suchas that in a transceiver. A controller may prepare every transceiver toreceive the beacon signal from the power receiver, (i.e., device to becharged). The device to be charged then sends out a beacon signal,(e.g., calibration signal that may be the same frequency of the phasedarray via, for example, a wireless communication between the array andthe receiver to sync up their clocks), that traverses all open pathsbetween the device to be charged and the power transmitter. The receivedsignal at the power transmitter is equivalent to the sum of all openpaths between the receiver and transmitter's antennae that lands on eachantenna in the power transmitter, with the sum of each path adding up toa specific power level and phase at every specific power transmitterantenna.

Each antenna in the transmitter array compares the incoming signal withan internal signal to detect the received phase. Once the received phaseis established by all the transmitter's antennas, each antenna transmitsback at the complex conjugate of the received phase with its full power.

In addition, since the above tuning of the array takes intoconsideration all possible paths, (e.g., there is no assumption thatthere is a direct open path between array and receiver or that thereceiver moves in smooth and linear motion in the environment), anychanges to the configuration of the environment may be equivalent to thereceiver being moved or the power transmitter array's physicalconfiguration being changed. Therefore frequent re-tuning of the arraymay be required constantly, (e.g., 10 or more times per second).

Since retuning the antenna array requires shutting off the power beingsent to “listen” to the receiver's beacon signal, time may be lost thatcould have been used to power the array. Accordingly, the array mayreduce the frequency of the retuning when the power level at thereceiver does not change significantly in order to maximize the powerdelivery to the receiver. When the power reception at the receiverdrops, the array may increase the frequency of the updates until thereceiver power stabilizes again. Specific limits on the frequency of thetuning may be set up, such as a minimum of 10 tps (tunings per second)to a maximum of 500 tps. Since very high frequency retuning might lowerthe efficiency of the power transfer beyond usefulness.

Alternatively, the tuning of a number (n) antennas may be performed asfollows. All n antennas may be switched off. One of the n antennas isthen turned on and left on as a reference for each of the other nantennas to tune. Each of the rest of the n antennas are then turned on,their optimal phase is recorded, and they are then turned off. When thissequence is performed on the nth antenna, all antennas are turned on attheir respective optimal phases.

With respect to the first embodiment having a moving receiver, all ofthe transmitter antennas may need to be re-tuned, for example by movingtheir phases slightly around their current values and detecting theimpact on the received signal. If it improves in one direction,cycling/incrementing the phase continues until there is no improvementto either side. This may depend on the ability to detect a change in thereceived power level for a large array, otherwise, the whole array mightbe required to switch off and re-establish the phases from thebeginning.

An exemplary array 101 a or 101 b can be a 30×30 grid net ofapproximately one meter per side, with each intersection of wires havinga single transmission antenna 204. Preferably array grid 101 a or 101 bis made of flexible/soft materials. Flexibility of grid material enablesa user to physically configure the microwave array emitter grid 101 a or101 b in a substantially non-uniform, non-coplanar manner, i.e., spreadout, but not flat, in order to minimize mirror focal points caused by,for example, flat, two dimensional arrays, and blind spots thatordinarily occur in flat, regularly disposed arrays having discretephase differences. As shown in FIGS. 1A-1B, either array 101 a or array101 b is sufficiently flexible so that it can be draped over a supportstructure, such as potted plant S, to provide the preferablynon-uniform, non-coplanar configuration.

In this manner, the inverse-square law is successfully challenged, sincethe phased antenna is directional, thereby creating gain via aconstructively phased beam signal that can be received at the receivingdevice 102. Moreover, use of a phased array, such as 101 a or 101 b,obviates the necessity of using a more cumbersome, unsightly device suchas a physical directional antenna, i.e., a dish, a Yagi, or the like.Additionally, due to the efficiency of the power transmission process,low power may be used for the transmission such that the electromagnetic(EM) signal can have most of its strength proximate the receiving deviceinstead of spread all over, in order not to harm the environment orcause interference with devices located elsewhere.

Once the signal is received and its power is available, the process ofconverting the approximately 5.80 GHz AC current coming from the antennainto a DC current to charge the battery 370, power storage capacitor, orthe like, is done with lower voltage rectifiers capable of the task.These rectifiers can either be based on small area Schottky diode orutilize a resonance with a 5.80 GHz oscillating circuit in the samephase as the received signal, thus enhancing its power to the point ofovercoming the voltage drop of the diodes used in the rectifier portionof the rectenna 340. It should be noted that multiple devices may becharged by time sharing the array, or by superimposing phases of theantennas in order to simulate a multiple beam configuration.

The charging mechanism described above operates when the transmitter andreceiver are in communication with one another. However, a method forcharging a receiver that has no power to communicate may be beneficialas well. To accomplish this, a location, or locations, that will receivea periodic power transmission burst may be established.

In one example of how to charge a device having no battery power, abeacon device, or resurrector, (not shown) may be placed in the locationto receive the periodic power transmission burst or on demand by theuser. The beacon device communicates with the power transmission grid,such as by transmitting a beacon signal, and the power transmission gridrecognizes that beacon signal phase configuration as a location totransmit a periodic power transmission burst, (e.g., a one second burstevery ten minutes, or a 0.1 second burst every minute with a one secondburst every ten minutes). The beacon signal transmitted from the beacondevice may be reflected and/or refracted through various media before itarrives at the power transmission grid. Accordingly, multiple beaconsignals may be received by the power transmission grid. When the powertransmission grid receives the one or more beacon signals, the openpath(s) from the location of the beacon device to the power transmissiongrid may be established.

The power transmission grid may then aggregate the beacon signals torecreate the waveform of the transmitted beacon signal. From thisrecreated waveform, the power transmission grid can then transmit thepower transmission burst as, for example, a reverse waveform of therecreated waveform to provide a power burst at the location establishedby the beacon device. In one embodiment, the reverse waveform may bedetermined by taking the complex conjugate, or mathematically equivalenttransform, of the waveforms received from the beacon device. The beacondevice can be turned off once the location to receive a periodic powertransmission burst is established.

The device to be charged 102 that has no battery power can then beplaced at that location where it will receive the periodic powertransmission burst until it has enough power to communicate with thepower transmission grid to undergo the charging process described above.The device can then be moved away from that location.

Once a device to be charged 102 is moved from one location to another,or the power transmission grid is moved, the power transmission grid mayre-tune itself, (e.g., re-align transmission antennas), to establish thebest transmission power to the device to be charged 102. This re-tuningmay occur in response to the device 102 reporting a drop in power or inregular intervals, (e.g., 1 ms-10 s). However, the regular interval maybe shortened or lengthened depending on how well the signal power ismaintained by the receiver, while continuing to re-tune regularlydespite no drop in power.

The transmitter antennas may also take the form of including circuitryinto a single chip and daisy chaining the chips with wires to createlong strips of “phased wires” that may be configured and used in variousshapes and designs. Constructing complex arrays with thousands ofantennas and associated controllers through strings of “phase control”chips, the wires between the chips may serve as the data pathsconnecting the chips to a common controller, while at the same time, thewires may also act as the transmitting/receiving antennas themselves.Each chip may have more wires coming out of it acting as antennas. Eachantenna may be given an address, (e.g., a, b, c, and the like), allowingthe chip to control the phase of each antenna independently from theothers. Additionally, the wires may be configured in all sorts ofarrangements, depending on available space since the tuning of the arrayis irrespective of the antenna locations and arrangements.

Since the antenna chip controllers are connected through short wires,the wires may be utilized as antenna in several ways. For example, thewires themselves may be driven by oscillator and/or amplifiers, or ashield may be used around the wires, with the shield itself driven andused as an antenna, thus preventing the communication wires fromshielding the signal in multi-layers arrays.

FIG. 4 is a block diagram of an alternative first embodimenttransmitter. The transmitter may be an antenna controller 400 thatincludes a control logic 410, phase shifters 420 (N Count), signalgenerator/multiplier 430, amplifiers 440 (N Count), and (N) antennas450. The antenna controller 400 receives power and base frequencycontrol signals, as well as other commands and communication signals, ona common bus from a single controller that controls all antennacontrollers or from a previous antenna controller 400. The power signal,for example, may be received by a power supply of the transmitter 400(not shown), while the base frequency control signal may be received bythe signal generator/multiplier 430, and the communication signals andcommands may be received by the control logic 410. In the case whereeach previous antenna controller 400 provides the power and basefrequency control signals, a bus carrying those signals may continue onto the next antenna controller 400. The control logic 410 may controlthe phase shifter 420 to cause it to adjust the phase of the amplifiers440. The signal generator/multiplier receives the signal from the busat, for example 10 MHz, and converts it up to for example 2.4, 5.8 GHzand the like for wireless transmission.

FIG. 5 is a block diagram of an alternative second embodimenttransmitter. The transmitter may be an antenna controller 500 thatincludes a control logic 510, phase shifters 520 (N count), signalgenerator/multiplier 530, transceivers 540 (N Count), (N) antennas 550,and phase comparators 560 (N Count). The transceivers 540 receive thecalibration or beacon signals from the receivers and forward the signalto the phase comparators 560. The phase comparators 560 determine thephase of the received signals of their respective transceivers 540 anddetermine an optimal phase angle for which to transmit the power signal.This information is provided to the control logic 510, which then causesthe phase shifter 520 to set the phase, (e.g., at the complex conjugateof the received beacon/calibration signal), of the transceivers andtransmit the power at that set phase. The signal generator/multiplier530 performs a function substantially similar to the signalgenerator/multiplier 430 of the antenna controller 400. In addition, thebus signals are similar to those in the transmitter 400, with thesignals being received, for example, by the counterpart components intransmitter 500.

FIG. 6 is block diagram of a controller 600 for controlling, forexample, the antenna controllers of FIGS. 4 and 5. The controller 600includes a control logic 610, power source 620, communication block 630connected to an antenna 660, base signal clock 640 connected to anantenna 670, and bus controller 650. The control logic 610 controls thebus controller 650, which transmits signals out on M buses to M numberof antenna controllers, (e.g., 400 and 500). The power source 620provides a source of power to the bus controller 650. The communicationblock 630 transmits and receives data from a receiver over itsrespective antenna 660. The base signal clock 640 transmits the basesignal to other controllers and may also send/receive transmissions tothe receiver for synchronization. One controller 600 may be utilized tocontrol all transmitter antennas or several controllers 600 may be usedwhere one controller 600 controls a group of antennas. Additionally, itshould be noted that although separate communication blocks and basesignal clock, having respective antennas are shown, the functionalitymay be incorporated into one block, (e.g., the communication block 630).

FIG. 7 is block diagram of an alternative receiver 700 in accordancewith the first embodiment. The receiver 700 includes a control logic710, battery 720, communication block 730 and associated antenna 760,power meter 740, and rectifier 750 and associated antenna 770. Thecontrol logic 710 transmits and receives a data signal on a data carrierfrequency from the communication block 730. This data signal may be inthe form of the power strength signal transmitted over the side channeldescribed above. The rectifier 750 receives the power transmissionsignal from the power transmitter, which is fed through the power meter740 to the battery 720 for charging. The power meter 740 measures thereceived power signal strength and provides the control logic 710 withthis measurement. The control logic 710 also may receive the batterypower level from the battery 720 itself.

The receiver 700 may be synchronized with, for example, the controller600 by having the controller 600 transmit the base frequency signal viathe antenna 670. The receiver 700 may then use this signal tosynchronize a beacon signal, or calibration signal, that the receivertransmits back to the controller 600. It may also be noted that thistechnique may be utilized with multiple controllers as well. That is,where multiple transmission arrays are being utilized, the controllersmay be synchronized with one another by utilizing a base frequencysignal sent from one of the controllers.

FIG. 8 is block diagram of an alternative receiver 800 in accordancewith the second embodiment. The receiver 800 includes a control logic810, battery 820, communication block 830 and associated antenna 870,power meter 840, rectifier 850, beacon signal generator 860 and anassociated antenna 880, and switch 865 connecting the rectifier 850 orthe beacon signal generator 860 to an associated antenna 890. Therectifier 850 receives the power transmission signal from the powertransmitter, which is fed through the power meter 840 to the battery 820for charging. The power meter 840 measures the received power signalstrength and provides the control logic 810 with this measurement. Thecontrol logic 810 also may receive the battery power level from thebattery 820 itself. The control logic 810 may also transmit/receive viathe communication block 830 a data signal on a data carrier frequency,such as the base signal clock for clock synchronization. The beaconsignal generator 860 transmits the beacon signal, or calibration signalusing either the antenna 880 or 890. It may be noted that, although thebattery 820 is shown for being charged and for providing power to thereceiver 800, the receiver may also receive its power directly from therectifier 850. This may be in addition to the rectifier 850 providingcharging current to the battery 820, or in lieu of providing charging.Also, it may be noted that the use of multiple antennas is one exampleimplementation and the structure may be reduced to one shared antenna.

Since the transmitter's antenna control circuits and the receiver powerand control circuits may be built as Integrated Chips (ICs), and mayshare several key circuit components, the two chip functionalities maybe designed as a single chip, and by choosing different packaging orconfiguration, the chip may function as either a transmitter orreceiver. That is, the same chip with certain portions enabled ordisabled may be utilized as a transmit antenna controller or a receivercontroller. This may reduce the cost of building and testing twodifferent chips, as well as save on chip fabrication costs, which may besignificant.

As discussed above, the shape of the transmission grid may take on manyvarieties. Accordingly, the packing of the antennas could be closeenough to around half a wavelength of the transmitted power signal, toseveral times the wavelength. Two-dimensional arrangements could be madeto allow the array to be laid flat under a carpet, or draped over atticheat insulation. For example, multiple wide wires, (e.g., narrow stripsof a two-dimensional array), may be employed that contain multipletransmitting antennas. These wide wires could be installed in flooringor within walls. Alternatively, the power transmission grid could be inthe form of loop antennas, or any other shape.

Three dimensional arrangements might pack the largest number of antennasand can be incorporated into convenient forms such as office ceilingtiles, doors, paintings and TVs—thus making the array invisible andnon-obtrusive. Also, grid arrays may be formed in several layers stackedbehind one another, allowing for a higher density antenna. In thisexample, the array acts similarly to a “phased volume” having a singleforward beam with a minimum of a mirror beam behind it. The mirror beammay be reduced as the thickness of the phased volume increases.

That is, perfectly flat phased arrays using omni-directional antennaemay create two “images” of the formed wavefronts symmetrically aroundthe plane of the array, (e.g., when there is free space or an identicalenvironment on opposite sides of the array). This could have undesirableconsequences of reducing the power delivery, (e.g., 50% of the powergoing to the backplane), and thus reducing the efficiency of thetransfer. Arranging the array antennae in non-planar form may reducethis symmetrical wavefront even if it has a 3-dimensional arraysymmetrical design, due to the fact that the antennas will havedifferent phases on across the symmetrical sides of the array, makingthe signal non-symmetrical and non-“mirrored”.

When the array is phase tuned for a particular receiver, every antennain the array has a specific phase to which it transmits to create asignal that reaches that particular receiver. Two or more receivers canbe configured to receive power by one or a combination of the followingtechniques.

In a first technique, time sharing the power delivery may be utilizedbetween the different receivers. This can be done by tuning the antennasin the array to one receiver, and then switching to the next receiver,giving each receiver an equal (or unequal) amount of time. The tuning ofthe array to each receiver may be done from memory or by re-tuning thearray using a process similar to the second embodiment technique.

In another technique, phase modulating all the array antennae to createmultiple power spots may be utilized. For each antenna, the receivedsignal is a vector with the phase being the received angle, while themagnitude is the power level of received signal. To create the returnedsignal to multiple receivers, the phase of the transmission may bedetermined as being the angle of the sum of the received vectors.Although it may not be necessary to utilize the magnitude of thereceived signal and transmit from each antenna at normal transmissionpower, in order to create a biased multi-focus signal that performsbetter when multipath signals are considered, the peak received signalpower from each receiver may be discovered, and the vector addition maybe biased by scaling the vectors against a normalized scale, (e.g., peakpower from each receiver may be considered of magnitude 1.0 for the peakpower). The addition of the vectors may ensure that each antennaprovides more power to the receiver that it delivers more power to, or,alternatively, receives more power from.

Antenna sharing is another technique. By dividing the whole array tomultiple sub-arrays, each may dedicate its power to a specific receiver.This approach may be beneficial when the array is large enough to beefficient when divided.

Separate arrays may be used in unison, where the individual array unitssynchronize their base signal clocks using a shared over the airfrequency to achieve a continuous signal from a designated “master”unit, allowing all “slave” transmitter controller units to add up theirwaveforms coherently. This allows the separate arrays to be distributedin the environment, giving the users flexibility in arranging multiplearrays around the building, living quarters, manufacturing plan oroffices. During setup of these controllers, an installer/manager maylink the different controller arrays to each other by designating amaster unit along with failover sequences such that no matter how manyarrays fail, the system will continue working using the availablearrays. For example, the arrays may be set by synchronizing them usingan atomic clock. That is, separate array units may work withoutsynchronizing on a base frequency by using accurate atomic clocks,(e.g., greater than 1:10̂10 accuracy), if the separate array unitsutilize a single frequency to use for power transmission. In this case,they would be in phase for fractions of a second, allowing coherency ofphase/signal to be maintained.

In another power transmission technique, the transmitter may send out aregular signal at the side communication channel broadcasting itspresence to all receivers. If there are other transmitters in thevicinity, it ensures to use one of the agreed upon frequencies, or avoidsignal collisions by monitoring other transmitter's signals. Thesebroadcast announcements can vary in frequency from several per minute toless than one per minute. The receiver may send out a signal announcingits presence, and the transmitters may negotiate to find which one isthe most suitable for the power transfer. Once decided, the receiver“locks” onto a single transmitter. This may require that eachtransmitter is defined as a logical (single controller) device—whichcould be made up of multiple linked transmitters. If the controllerdetects that the power envelope has changed, (i.e., a receiver is notrequiring the same power), the controller may continue to provide powerso that the receiver will not fail.

In another power transmission technique, the transmitters could be setup such that they are open to serve power to any wanting device, or theycould be “paired” with the devices they should serve. Pairing avoids theproblem of the neighbors' borrowing power from each otherunintentionally, which could affect the efficiency from thetransmitter's owner point of view. When the transmitter is confrontedwith multiple receivers, it may want to establish a hierarchy forprioritization, such as giving the most needy devices the power first,which could be established on one or more predefined criteria.

For example, some of the criteria may include: the device is of criticalimportance to its owner, (e.g., a cell phone as opposed to a toy); thedevice does not typically spend all day in the vicinity of thetransmitter, (e.g., a TV remote control compared to a cell phone); orthe device is found to need immediate power or it will fail. Suchdevices may be given higher priority over others until they reachnon-critical power. Alternatively, a user customized priority may beutilized, whereby the user decides which device should get the highestpriority.

The example prioritization preference described above may bepre-installed into the transmitter system, (e.g., in the control logic),with the ability to be overruled by the installer of the array, ensuringthat the system is delivering on the prioritization of the owners/users.The owner or user may also desire whether the array would be open todeliver power to any device, or may desire to register specific devicesas highest priority or least priority. Additionally, the user or ownermay desire to determine whether or not to maintain power to specificdevice even if it is moving.

In the second embodiment array tuning algorithm, the transmission ofpower has to be stopped as the array re-tunes to a new location of thereceiver. If these re-tune operations are done at a high frequency dueto fast movement of the receivers or due to rapid changes in theconfiguration of the environment, the time needed to keep the arrayturned off while receiving a new beacon signal could reduce the powerdelivery efficiency. Accordingly, to counteract this, more than onefrequency may be used by the array/receiver. While one frequency isbeing tuned, another frequency may continue to transmit power, then thesubsequent frequency is tuned until all the frequencies have re-tuned,thus avoiding any stopped gaps in the transmission.

When designing large phased arrays, having to send the requiredfrequency to every antenna may be difficult due to the large number ofcables, (e.g., coaxial). This may be even more difficult when the numberof antennas reaches over 1000. In another alternative, therefore,instead of sending a high frequency signal (>1 GHz) to all the antennas,a lower frequency signal (˜10 MHz) may be transmitted through to all theantennas, and every antenna would have frequency multiplicationcircuitry such as Phased Locked Loop (PLL) and phase shifter.

Additionally, a standard format battery, (e.g., AA, AAA, C-cell, D-cellor others), with ability to receive power and recharge itself might bedesired as a replacement for a disposable or rechargeable batteries usedin an electronic/electrical device. This would require the battery tohave all the circuitry needed to communicate with the transmitter array,as well as have charge/energy capacitance to be used to run the devicethe battery powers.

The device often requires voltage or current to activate the componentsor battery capacitance to ensure long operation between battery swaps,that exceeds the capability of single battery. Therefore multiplebatteries are often used in series or in parallel. However, with asingle receiver battery, only one battery can be necessary for deviceoperation, since the battery can deliver the required voltage and theenergy capacity becomes a moot issue since the battery is able toreceive copious amounts of energy to maintain operation perpetuallywithout need for changing the batteries.

However, using a single battery in place of several batteries may notwork due to the configuration of the devices battery storage area.Accordingly, additional techniques may be employed to overcome this.

FIG. 9 is a block diagram of a receiver battery system 900. The system900 includes at least one receiver battery 910 and may include anynumber of null batteries 920. For purposes of example, one receiverbattery 910 is shown and two null batteries 920, however, it should benoted that any number of null batteries may be utilized. The receiverbattery 910 includes a power capacitor 911, a control circuit 912, and avoltage control oscillator 913. The null battery 920 includes inductionlogic 921.

Accordingly, the battery system 900 may operate as follows. Only onebattery with the “receiver” enabled battery, (i.e., 910) is provided.However, used regular batteries placed in series with a good runningbattery may have their resistance build up over time, and they couldleak once their lifetime usage is exceeded, among other problems thatcan occur.

Alternatively, “null” batteries, (i.e., 920), may be used in conjunctionwith a “power selector” on the receiver battery 910. The null batteries920 in one example are devices with exact battery dimensions but withtheir anodes shortened, making the voltage of the receiver battery 910drive the device unaided. The receiver battery 910 utilizes the controlcircuitry or slider 912 or other selection mechanism to allow the userto select the number of batteries he/she is replacing. The receiverbattery 910 then outputs the desired voltage to compensate for the nullbatteries 920.

In another technique, intelligent null-batteries 920 as well as anintelligent receiver battery 910 may be used. The receiver battery willinitially output the voltage of one battery of the desired format aswell as 1 KHz (or similar other frequency) low voltage oscillation(<0.1V oscillation for the duration of detecting the number of nullbatteries used), and the intelligent null-batteries 920 use the 1 KHz topower themselves inductively. The null batteries now create an effect onthe power-line by resistance, capacitance or other means that thereceiver battery can detect. The frequency of effect of the intelligentnull-batteries 920 is done by onboard quasi-random generators, (e.g.,logic 921), that have the characteristic of being statisticallyadditive. It can therefore be determined the count of the quasi-randomgenerators on the line. One embodiment of this would be the use of a32-bit linear feedback shift register running at a known interval, suchthat the shifted bit is used to trigger the effect “blips” on the powerline. The seed number of the feedback shift registers on power up shouldbe different on all the null batteries 920 so they do not work inunison.

FIG. 10 is an example battery system power line diagram 1000, including“blips” 1010. The receiver battery 910 counts the blips 1010 on thepower line and determines the number of intelligent null-batteries 920.The blips 1010 could be high frequency pulses or capacitance modifiers.Blips that are not masked out by most electrical/electronic devices maybe chosen. This process is performed for a short period of time, forexample, less than 1 millisecond. After that, the receiver battery 910does not require voltage detection until a next power-up which could bein a different device with different power needs. The 1 KHz “power”frequency created by the receiver battery 910 stops and the nullbatteries 920 become dormant and become transparent to the device beingpowered.

Referring again to FIG. 10, random blips 1010 are generated by each ofthe two null batteries 920 over the power system line of system 900. Theblips 1010 are used to determine the number of random blip generators bythe receiver battery 910. By counting the blips over time, and dividingby the expected number from a single null battery 920, it can bedetermined the number of null batteries 920 installed in series. In aparallel battery installation system, however, one receiver battery 910may be required for each parallel power line.

When a device is receiving power at high frequencies above 500 MHz, itslocation may become a hotspot of (incoming) radiation. So when thedevice is on a person, the level of radiation may exceed the FCCregulation or exceed acceptable radiation levels set bymedical/industrial authorities. To avoid any over-radiation issue, thedevice may integrate motion detection mechanisms such as accelerometersor equivalent mechanisms. Once the device detects that it is in motion,it may be assumed that it is being manhandled, and would trigger asignal to the array either to stop transmitting power to it, or to lowerthe received power to an acceptable fraction of the power. In caseswhere the device is used in a moving environment like a car, train orplane, the power might only be transmitted intermittently or at areduced level unless the device is close to losing all available power.

FIG. 11 is an alternative receiver 110 in accordance with the firstembodiment that includes motion detection as described above. Thereceiver 1100 includes a control logic 1110, battery 1120, communicationblock 1130 and associated antenna 1160, power meter 1140, rectifier 1150and associated antenna 1170, and a motion sensor 1180. With theexception of the motion sensor 1180, the rest of the components operatefunctionally similar to the respective components of receiver 700. Themotion sensor 1180 detects motion as described above and signals thecontrol logic 1110 to act in accordance with the technique describedabove.

FIG. 12 is an alternative receiver 1200 in accordance with the secondembodiment that includes motion detection as described above. Receiver1200 includes a control logic 1210, battery 1220, communication block1230 and associated antenna 1270, power meter 1240, rectifier 1250,beacon signal generator 1260 and an associated antenna 1280, and switch1265 connecting the rectifier 1250 or the beacon signal generator 1260to an associated antenna 1290. With the exception of the motion sensor1280, the rest of the components operate functionally similar to therespective components of receiver 800. The motion sensor 1280 detectsmotion as described above and signals the control logic 1210 to act inaccordance with the technique described above.

A device designed to receive power at frequencies used by WiFicommunication or Bluetooth and the like such as a cell phone or mediaplayer might already have antennas capable of receiving power at thepower transmission frequencies. Accordingly, instead of havingadditional antennas to receive the power, the same communicationantennas used for the WiFi communication and the like may be used toreceive power, by adding the required circuitry to the communicationhardware, (e.g., adding rectification, control logic, etc.).

Some example uses of the wireless power transmission system may includesupermarket and consumer retail outlets provide pricing tags on theshelves of the merchandise. Managing the price number on these tags canbe an expensive and time consuming effort. Also, special deals andpromotions mean that the tags would be changed daily.

With today's electronic ink signage, it is possible to have each tagmade of a small electronic device that displays the prices/promotionsquite effectively, and electronic ink consumes no power while displayinga static image. However, power is required to receive the new data todisplay and it is also required to change the electronic ink display.Having wires reaching every tag is not a feasible solution nor is havingbatteries in each tag. Since they would require charging or replacementregularly. By utilizing wireless power transmission, thousands of tagscan be maintained operational from wireless power transmitter arraysplaced in the ceilings or shelves; powering the tags on regular basis,as well as when a tag is moved. Once the tags arrive at the desireddestination, the tags may be activated with initial power either wiredor wireless.

In another example, manufacturing plants utilize a large number ofsensors and controllers to maintain synchronization of production,overall productivity and quality of manufactured goods. Despite the useof wireless communication, it is still required to run power carryingwires to every device, which makes the devices dependent on one morecomponent that is prone to failure, and the devices cannot behermetically sealed before installation for use in highly combustibleenvironments such as oil refineries, since the devices need to haveholes to bring the power wires into the device. Accordingly, wirelesspower may be provided to these devices by incorporating one of thewireless power receivers described above.

The wireless power system may also be utilized for motion detection.When the power transmission system is active, small disturbances in theenvironment can change the efficiency of the transfer, even when thechange is not in the line of sight of the transmission. Since thissystem leverages the multiple paths (multipath) in the environment, itcan be used as a motion detector. By measuring the power received froman array that is localized or distributed in the environment, anychanges to the power level received will be an indication of changes tothe electromagnetic configuration of the environment. It may be notedthat in such uses, the power transfer level can be very small, sincewires can power the receiver, but is acting only as means of tuning thearray. Once a change in the environment's configuration is detected, thesecurity system/alarms may be notified of the change.

In another example, individual drink and food containers that regulatethe temperature of their contents need to have a constant power source.If these containers are highly mobile, it becomes difficult to maintainthe power source availability. Wireless power can be used to maintain apower source availability and hence the temperature of the containerscan be maintained at the desired temperature. The containers can alsouse the available power to report the contents temperature, level offluid or weight of contents. An example of this is when cold/hot drinksare served on hot days, or when drinking them cold/hot is the best wayto drink them, with this capability, the drinker does not have to finishtheir drink before it reaches the ambient temperature, but could enjoytheir drinks on a longer time period. Also, when the drinks are gettinglow, a host can be wirelessly notified through a signal receiver and cantop up the drinks in time before they run out.

In another example, when you can monitor the power usage of the devicesusing power receivers, it is possible to detect failed devices prior tofailure. For example fire alarms may be considered as having failed ifthey are not consuming the nominal power they use, or when powerconsumption of a device changes drastically, which usually occurs when adevice is about to fail.

It is to be understood that the present invention is not limited to theembodiments described above, but encompasses any and all embodimentswithin the scope of the following claims. For example, although afrequency of 5.8 GHz has been described above, any frequency over 100MHz may be utilized for the power transmission frequency.

It should also be noted that any type of rechargeable batteries may beutilized to receive the charge from the power transmission grid,including standard size rechargeable batteries or custom rechargeablebatteries for use in specific electronic devices, (i.e., cell phones,PDAs, and the like). These rechargeable batteries may be utilized toreplace the currently existing batteries and may include the electronicsof the receiver that will allow them to receive the power transmissionsignal and convert it to recharge the batteries.

What is claimed is:
 1. A wireless sensor, comprising: a wirelessmicrowave power receiver, comprising: one or more rectennas configuredto receive power transmission signals from a wireless microwave powertransmitter to charge the wireless microwave power receiver; wherein thewireless microwave power transmitter comprising: a controller and aphased array antenna having a plurality of microwave array transceiversfor transmitting the microwave power transmission signals, thetransceiver being adaptively-phased by the controller to transmit thepower transmission signals at a respective selected phase; eachtransceiver further operable to receive multipath calibration signalsfrom the microwave power receiver and detect a phase at which each ofthe multipath calibration signals is received by the transceiver; atransmitter configured to transmit said multipath calibration signals tosaid microwave power transmitter; and, wherein each rectenna is furtherconfigured to receive a power transmission signal having a determinedphase, the determined phase of the power transmission signal generatedunder the control of the controller at the microwave power transmitterbeing substantially a complex conjugate of a detected phase of thecalibration signal; and wherein the microwave power transmitter andwireless microwave power receiver are not required to be in line ofsight of each other; and wherein the controller is further configured todetermine a prioritization order for transmission of the powertransmission signals to the wireless microwave power receiver based upona predefined criteria.
 2. The wireless sensor of claim 1 wherein thedetermined phase is a phase angle within a margin of deviation from thecomplex conjugate of the detected phase of the calibration signal. 3.The wireless sensor of claim 2 wherein the determined phase is a phaseangle within plus or minus 36 degrees of the complex conjugate of thedetected phase of the calibration signal.
 4. The wireless sensor ofclaim 1 wherein the predefined criteria includes any of the following:the wireless microwave power receiver is paired with the wireless powertransmitter, the wireless microwave power receiver has a greater needfor power than another wireless microwave power receiver, or thewireless microwave power receiver includes a higher rank than anotherwireless microwave power receiver.
 5. The wireless sensor of claim 1,wherein the wireless sensor is hermetically sealed.
 6. The wirelesssensor of claim 1, further comprising: a sensing device configured tosense at least one environmental condition; and a transceiver configuredto transmit information relating to the sensed environmental condition.7. The wireless sensor of claim 6 wherein the transceiver is configuredto receive control information wirelessly from a source indicating acontrol command relating to the sensed environmental condition.
 8. Thewireless sensor of claim 6 wherein the at least one environmentalcondition includes any one of the following: heat, light, radiation ormotion.